Fibrous joinery interface between structures

ABSTRACT

An implantable medical device includes a first component including a first material, a second component including a second material, and a fiber matrix including a plurality of fibers. The fiber matrix joins the first component to the second component. The fiber matrix includes a first a first portion connected to the first component, and a second portion connected to the second component. The first portion of the fiber matrix is interpenetrated with, and mechanically fixed to, the first material. The first portion of the fiber matrix directly contacts the first material.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Provisional Application No.62/093,872, filed Dec. 18, 2014, which is herein incorporated byreference in its entirety.

TECHNICAL FIELD

The present invention relates to a structure for joining materials thatare not readily bondable to each other. More specifically, the inventionrelates to structures and methods for joining components of a medicaldevice that are not readily bondable to each other.

BACKGROUND

Medical devices, particularly implantable medical devices, often consistof a variety of materials having physical characteristics beneficial fora specific application. For example, implantable medical leads may beformed from a biocompatible polyurethane polymer, such as athermoplastic polycarbonate polyurethane. In some embodiments, it may bedesirable to attach an external non-polyurethane polymer, such as asilicone polymer, component to at least a portion of an implantablemedical lead. For example, creating a joint that attaches a siliconepolymer to a polyurethane polymer may require a series of complexprocessing operations, for example preparing the polyurethane polymerand/or silicone polymer surfaces, because silicone polymer andpolyurethane polymer are typically not readily bondable to each other.In some embodiments, such processing may include plasma treating apolyurethane polymer surface to clean and/or chemically activate thesurface. The process may additionally or alternatively include applyinga primer or adhesive to the polyurethane polymer surface beforeapplying, such as overmolding, the silicone polymer onto the preparedpolyurethane polymer surface. Often such complex processing must becompleted in a short span of time because the polyurethane polymersurface may begin to deteriorate after it is prepared. If thepolyurethane polymer surface deteriorates to a certain extent, the jointthat forms between the silicone polymer and the polyurethane polymer maynot have adequate strength.

Other material combinations in which the materials are not readilybondable to each other may require similarly complex processing. Examplematerial combinations include silicone polymer and polyether etherketone. Additionally many thermoplastics cannot be readily heat bondedto thermoset polymers, and require additional processing. Joiningmaterials which are not readily bondable to each other may requiresurface treatment and/or adhesives which may take significant time tocure, thus slowing production of the medical devices and increasingtheir cost. What is needed is a better method for joining materials thatare not readily bondable to each other.

SUMMARY

In Example 1, an implantable medical device includes a first componentincluding a first material, a second component including a secondmaterial, and a fiber matrix including a plurality of fibers, the fibermatrix joining the first component to the second component. The fibermatrix includes a first portion of the fiber matrix connected to thefirst component; and a second portion of the fiber matrix connected tothe second component. The first portion of the fiber matrix isinterpenetrated with, and mechanically fixed to, the first material. Thefirst portion of the fiber matrix directly contacts the first material.

In Example 2, the device of Example 1, wherein the first material is asilicone polymer, the second material is a polyurethane polymer, and thefiber matrix is a polyurethane polymer.

In Example 3, the device of any of Examples 1-2, wherein at least someof the plurality of fibers in the second portion of the fiber matrix aredistinctly identifiable within the second component.

In Example 4, the device of any of Examples 1-3, wherein the secondportion of the fiber matrix is bonded to the second component by a heatbond.

In Example 5, the device of any of Examples 1-3, wherein the secondportion of the fiber matrix is interpenetrated with, and mechanicallyfixed to, the second material, and wherein the second portion of thefiber matrix directly contacts the second material.

In Example 6, the device of Example 5, wherein the first material is asilicone polymer, the second material is a polyurethane polymer, and thefiber matrix is an aliphatic polyamide polymer.

In Example 7, the device of any of Examples 1-6, wherein each fiber ofthe plurality of fibers has a diameter between 0.1 micrometers and 2micrometers.

In Example 8, the device of any of Examples 1-7, wherein at least someof the plurality of fibers include a single fiber extending a pluralityof times between the first component and the second component.

In Example 9, a method for joining a first component and a secondcomponent of an implantable medical device includes: interpenetrating afirst portion of a fiber matrix within a first material, the firstmaterial being in a liquid state; forming the first component bysolidifying the first material, wherein the first portion of the fibermatrix is mechanically fixed within a portion of the first component anda second portion of the fiber matrix projects from the first component;and connecting the second portion of the fiber matrix to the secondcomponent to join the first component to the second component.

In Example 10, the method of Example 9, wherein interpenetrating thefirst portion of the fiber matrix within the first material includeselectro-spinning a fiber directly into the first material.

In Example 11, the method of Example 9, wherein interpenetrating thefirst portion of the fiber matrix within the first material includeselectro-spinning a plurality of fibers onto a substrate to form thefiber matrix, and overmolding the first material onto the fiber matrixon the substrate.

In Example 12, the method of any of Examples 9-11, wherein solidifyingthe first material is by cross-linking portions of the first materialaround portions of the first portion of the fiber matrix.

In Example 13, the method of any of Examples 9-12, wherein connectingthe second portion of the fiber matrix to the second component includesheat bonding the second portion of the fiber matrix to the secondcomponent.

In Example 14, the method any of Examples 9-12, wherein connecting thesecond portion of the fiber matrix to the second component includesinterpenetrating the second portion of the fiber matrix within a liquidsolution including a first portion of the second material, solidifyingthe first portion of the second material evaporating a solvent from theliquid solution such that the second portion of the fiber matrix ismechanically fixed within the first portion of the second component, andforming the second component by heat bonding a second portion of thesecond component to the first portion of the second component such thatat least a portion of the second portion of the fiber matrix isdistinctly identifiable within the second component.

In Example 15, the method of Example 14, wherein the first material is asilicone polymer, the second material is a polyurethane polymer, and thefiber matrix is an aliphatic polyamide polymer.

In Example 16, a joint structure between two components of animplantable medical device includes: a first component made of a firstmaterial; a second component made of a second material; and a fibermatrix including a plurality of fibers. The fiber matrix joins the firstcomponent to the second component. The fiber matrix includes a firstportion of the fiber matrix connected to the first component, and asecond portion of the fiber matrix connected to the second component.The first portion of the fiber matrix is interpenetrated with, andmechanically fixed to, the first material. The first portion of thefiber matrix directly contacts the first material.

In Example 17, the joint structure of Example 16, wherein the firstmaterial is a silicone polymer, the second material is a polyurethanepolymer, and the fiber matrix is a polyurethane polymer.

In Example 18, the joint structure of and of Examples 16-17, wherein atleast some of the plurality of fibers in the second portion of the fibermatrix are distinctly identifiable within the second component.

In Example 19, the joint structure of any of Examples 16-18, wherein thesecond portion of the fiber matrix is connected to the second componentby a heat bond.

In Example 20, the joint structure of Example 16, wherein the secondportion of the fiber matrix is interpenetrated with, and mechanicallyfixed to, the second material, and wherein the second portion of thefiber matrix directly contacts the second material.

In Example 21, the joint structure of Example 20, wherein the firstmaterial is a silicone polymer, the second material is a polyurethanepolymer, and the fiber matrix is an aliphatic polyamide polymer.

In Example 22, the joint structure of any of Examples 16-21, whereineach fiber of the plurality of fibers has a diameter between 0.1micrometers and 2 micrometers.

In Example 23, the joint structure of any of Examples 16-22, wherein atleast some of the plurality of fibers are randomly oriented.

In Example 24, the joint structure of Example 16-23, wherein at leastsome of the plurality of fibers include a single fiber extending aplurality of times between the first component and the second component.

In Example 25, a method for joining a first component and a secondcomponent of an implantable medical device includes: interpenetrating afirst portion of a fiber matrix within a first material, the firstmaterial being in a liquid state; forming the first component bysolidifying the first material, wherein the first portion of the fibermatrix is mechanically fixed within a portion of the first component anda second portion of the fiber matrix projects from the first component;and connecting the second portion of the fiber matrix to the secondcomponent to join the first component to the second component.

In Example 26, the method of Example 25, wherein interpenetrating thefirst portion of the fiber matrix within the first material includeselectro-spinning a fiber directly into the first material.

In Example 27, the method of Example 25, wherein interpenetrating thefirst portion of the fiber matrix within the first material includeselectro-spinning at least one fiber onto a substrate to form the fibermatrix, and overmolding the first material onto the fiber matrix on thesubstrate.

In Example 28, the method of any of Examples 25-27, wherein solidifyingthe first material is by cross-linking portions of the first materialaround portions of the first portion of the fiber matrix.

In Example 29, the method of any of Examples 25-28, wherein connectingthe second portion of the fiber matrix to the second component includesheat bonding the second portion of the fiber matrix to the secondcomponent.

In Example 30, the method of any of Examples 25-28, wherein connectingthe second portion of the fiber matrix to the second component includes:interpenetrating the second portion of the fiber matrix within a liquidsolution including a first portion of the second material; solidifyingthe first portion of the second material evaporating a solvent from theliquid solution such that the second portion of the fiber matrix ismechanically fixed within the first portion of the second component; andforming the second component by heat bonding a second portion of thesecond component to the first portion of the second component such thatat least a portion of the second portion of the fiber matrix isdistinctly identifiable within the second component.

In Example 31, the method of Example 30, wherein the first material is asilicone polymer, the second material is a polyurethane polymer, and thefiber matrix is an aliphatic polyamide polymer.

In Example 32, an implantable medical device includes a first tubularstructure, a second tubular structure coaxial with the first tubularstructure, and a fiber matrix joining the first tubular structure to thesecond tubular structure. The fiber matrix includes: a first portion ofthe fiber matrix interpenetrated within, and mechanically fixed to, thefirst tubular structure; and a second portion of the fiber matrixconnected to the second tubular structure. The first portion of thefiber matrix directly contacts the first tubular structure.

In Example 33, the device of Example 32, wherein the second tubularstructure is at least partially within the first tubular structure.

In Example 34, the device of any of Examples 32-33, wherein the firsttubular structure is made of a silicone polymer, the second tubularstructure is made of a polyurethane polymer, and the fiber matrix ismade of a polyurethane polymer.

In Example 35, the device of any of Examples 32-33, wherein the firsttubular structure is a silicone polymer, the second tubular structure isa polyurethane polymer, and the fiber matrix is an aliphatic polyamidepolymer; and wherein the second portion of the fiber matrix isinterpenetrated with, and mechanically fixed to, the second tubularstructure, and wherein the second portion of the fiber matrix directlycontacts the second tubular structure.

While multiple embodiments are disclosed, still other embodiments of thepresent invention will become apparent to those skilled in the art fromthe following detailed description, which shows and describesillustrative embodiments of the invention. Accordingly, the drawings anddetailed description are to be regarded as illustrative in nature andnot restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an exemplary implantable medical device.

FIGS. 2A-2C are schematic views of a portion of the implantable medicaldevice shown FIG. 1.

FIGS. 3A-3C are schematic views of a component of the implantablemedical device shown in FIGS. 2A-2C.

FIG. 4 is a schematic view of an alternative embodiment of a portion ofthe implantable medical device shown in FIG. 1.

While the invention is amenable to various modifications and alternativeforms, specific embodiments have been shown by way of example in thedrawings and are described in detail below. The intention, however, isnot to limit the invention to the particular embodiments described. Onthe contrary, the invention is intended to cover all modifications,equivalents, and alternatives falling within the scope of the inventionas defined by the appended claims.

DETAILED DESCRIPTION

A more complete understanding of the present invention is available byreference to the following detailed description of numerous aspects andembodiments of the invention. The detailed description of the inventionwhich follows is intended to illustrate but not limit the invention.

In accordance with various aspects of the disclosure, an implantablemedical device can be an implantable medical electrical device, such asa medical electrical lead discussed below.

FIG. 1 is a schematic illustration of a lead system 100 for deliveringand/or receiving electrical pulses or signals to stimulate, shock,and/or sense a heart 102. The lead system 100 includes a pulse generator105 and a medical electrical lead 110. The pulse generator 105 includesa source of power as well as an electronic circuitry portion. The pulsegenerator 105 may be a battery-powered device which generates a seriesof timed electrical discharges or pulses. The pulse generator 105 isgenerally implanted into a subcutaneous pocket made in the wall of thechest. Alternatively, the pulse generator 105 may be placed in asubcutaneous pocket made in the abdomen, or in another location. Itshould be noted that while the medical electrical lead 110 isillustrated for use with a heart 102, the medical electrical lead 110 issuitable for other forms of electrical stimulation/sensing as well.

In some embodiments, the medical electrical lead 110 extends from aproximal end 112, where it is coupled with the pulse generator 105 to adistal end 114, which is coupled with a portion of the heart 102, whenimplanted or otherwise coupled therewith. The medical lead 110 includesa lead body 116 extending generally from the proximal end 112 to thedistal end 114. The lead body 116 may be a tubular structure. Disposedalong a portion of the medical electrical lead 110, for example near thedistal end, may be at least one electrode 118 which electrically couplesthe medical electrical lead 110 with the heart 102. At least oneelectrical conductor (not shown) may be disposed within the lead body116 and extend generally from the proximal end 112 to the distal end114. The at least one electrical conductor electrically couples theelectrode 118 with the proximal end 112 of the medical electrical lead110. The electrical conductor carries electrical current and pulsesbetween the pulse generator 105 and the electrode 118, and to and fromthe heart 102.

In some embodiments, lead body 116 may include a first component 120made of a first material and a second component 122 made of a secondmaterial. The first component 120 may extend from the distal end 114,and the second component 122 may extend from the proximal end 114. Thefirst component 120 and the second component 122 may be connected at alead body transition 124 to form the lead body 116. In some embodiments,the second material may be different from the first material to imbuedifferent portions of lead body 116 with different beneficial physicalcharacteristics. For example, in some embodiments, the first materialmay be a very flexible and easily compliant material, such as silicone,to permit the first component 120, a portion of which may be adjacent toor within the heart 102, to easily conform to changes in the shape ofthe heart 102 as it beats. In contrast, in some embodiments, the secondmaterial may be a less flexible, less compliant material, such aspolyurethane, to provide the second component 122 with the stiffnessnecessary to accurately control the positioning of the lead body 116. Insome embodiments, the first material and the second material may not bereadily bondable to one another. Two materials may be considered readilybondable if the materials can be directly joined to each other withoutthe use of a surface treatment (other than surface cleaning) or anintervening third material such as, for example, an adhesion promoter oran adhesive. This presents a challenge in embodiments in which it isdesired that the first component 120 be securely connected to the secondcomponent 122 at lead body transition 124 to form lead body 116.Embodiments described below employ a fiber matrix to securely connect orattach two components made of materials that do not readily bond to eachother. Although the embodiments below illustrate connecting togethercomponents of a lead body, it is understood that the present inventionis suitable for a connection between any two surfaces of an implantablemedical device.

FIGS. 2A-2C are schematic views of a portion of the implantable medicalelectrical lead 110 shown in FIG. 1. FIGS. 2A and 2B are, respectively,longitudinal and axial cross-sectional views of a portion of the medicalelectrical lead 110 showing a portion of the lead body 116 including thelead body transition 124 connecting the first component 120 to thesecond component 122. As shown in FIG. 2A, in some embodiments the firstcomponent 120 may include a first inner lead surface 126, a first lumen128, and a first transition surface 130. The first lumen 128 may bedefined by the first inner lead surface 126, and may extend generallyfrom any location along the first component 120 to the lead bodytransition 124. As shown in FIG. 2A, in some embodiments, the secondcomponent 122 may include a second transition surface 132, a transitionstop 134, a second inner lead surface 136, and a second lumen 138. Thesecond lumen 138 may be defined by the second inner lead surface 136,and may extend generally from any location along the second component122 through the lead body transition 124. Together, the first lumen 128and the second lumen 138 form a lumen that may run the length of, andalong the axis lead body 116, and overlap at the lead body transition124.

As shown in FIGS. 2A and 2B together, in some embodiments, the secondtransition surface 132 is a radially outward facing surface of thesecond component 122 that may be at an end of the second component 122opposite the proximal end 112 (FIG. 1), and may be recessed radiallyfrom an outer surface of lead body 116 at the transition stop 134. Insome embodiments, the first transition surface 130 is a portion of thefirst inner lead surface 126 that may be at an end of the firstcomponent 120 opposite the distal end 114 (FIG. 1). As shown in FIG. 2A,in some embodiments, an end of the first component 120 butts up againstthe transition stop 134 and the lead body transition 124 extends fromthe transition stop 134 to an end of the second transition surface 132opposite the transition stop 134.

As shown in FIGS. 2A and 2B, in some embodiments, the second transitionsurface 132 may be adjacent to, and may be in contact with, the firstinner lead surface 126 at the first transition surface 130. In someembodiments, the first component 120 and the second component 122 may bephysically joined at first transition surface 130 and second transitionsurface 132, forming lead body transition 124. In some embodiments, thejoint structure between the first transition surface 130 and the secondtransition surface 132 securely connects the first component 120 to thesecond component 122.

FIG. 2C is a schematic enhanced view showing a portion of the jointstructure connecting the first component 120 to the second component122, according to some embodiments. As shown in FIG. 2C, the jointstructure may include a fiber matrix 140, including a first portion 142and a second portion 144. The fiber matrix 140 may include a pluralityof fibers and spaces between fibers, as described below. As shown inFIG. 2C, the first portion 142 may be connected to the first component120 at the first transition surface 130. The first portion 142 may beinterpenetrated with the first component 120. That is, the firstmaterial of the first component 120 may be intermingled with, and fillat least some of the spaces between, fibers in the first portion 142 ofthe fiber matrix 140. Thus, the first portion 142 may be mechanicallyfixed to the first component 120 without a need for a third material,such as but not limited to an adhesive and/or primer, between the firstcomponent 120 and the second component 122. Because the first portion142 may be mechanically fixed to the first component 120, the fibermatrix 140 may be made of a material that does not bond readily to thefirst material of the first component 120. In some embodiments, thefirst portion 142 directly contacts the first material of the firstcomponent 120, as there is no need for a third material between thefirst portion 142 and the first component 120.

As further shown in FIG. 2C, the second portion 144 of the fiber matrix140 may connect to the second component 122 at the second transitionsurface 132. In some embodiments, the fiber matrix 140 may be made of amaterial that bonds readily to the second material. In otherembodiments, the fiber matrix 140 may be made of the second material. Insuch embodiments, the second portion 144 may be readily bonded to thesecond component 122 at the second transition surface 132 by, forexample, heat bonding. A heat bond may be formed when a material, suchas the second material, is heated enough to soften the material, but notcompletely melt the material. In some embodiments, as the secondcomponent 122 and the fiber matrix 140 soften, the second portion 144moves into the second component 122 at the second transition surface132, forming a heat bond. In some embodiments, the heat bonding leavesat least some of the plurality of fibers in the second portion 144 ofthe fiber matrix 140 distinctly identifiable within the second component122 for a stronger bond than if all of the fibers of the second portion144 were uniformly incorporated into the second component 122.

FIG. 2C (and FIGS. 3C and 4 described below) is a schematicrepresentation of the fiber matrix 140, with the fiber matrix 140 shownas horizontal blocks with well-defined, parallel edges. However, it isunderstood that the edges in some embodiments may not necessarily bewell-defined, or parallel, and may be curved, uneven, and or notwell-defined.

In some embodiments, by employing a fiber matrix, the joint structuredescribe above in reference to FIGS. 2A-2C may connect two componentsmade of different materials that are not readily bondable to each other.In addition, the processing steps in some embodiments may be generallysimple and fast (e.g. heat bonding takes only seconds). Further, becauseno special surface treatment or adhesion promoters may be required, thejoint structure may not be susceptible to the same surface deteriorationthat requires certain processing steps to be completed in a short spanof time.

In some embodiments as described above in reference to FIGS. 2A-2C, thefirst material may be, for example, a silicone polymer, and the secondmaterial may be a polyurethane polymer. In other embodiments, the firstmaterial may be silicone polymer, and the second material may be apolyether ether ketone.

FIGS. 3A-3C are schematic views of the first component 120 of theimplantable medical device shown in FIG. 1, prior to joining to thesecond component 122 at lead body transition 124, as shown in FIGS.2A-2C, according to some embodiments. FIGS. 3A and 3B are, respectively,longitudinal and axial cross-sectional views of a portion of the firstcomponent 120. FIG. 3B shows a schematic cross-sectional view of thefirst component 120 shown in FIG. 3A. FIGS. 3A and 3B show the firstcomponent 120 including the first transition surface 130 and the firstlumen 128.

FIG. 3C is a schematic enhanced cross-sectional view of a portion of thefirst transition surface 130 prior to being connected to secondcomponent 122. FIG. 3C illustrates the fiber matrix 140, including thefirst portion 142 and a second portion 144. According to someembodiments, as shown in FIG. 3C, the first portion 142 may be connectedto the first component 120, while the second portion 144 may projectfrom the first transition surface 130 and into the first lumen 128. Thefirst portion 142 may be interpenetrated with the first component 120 asdescribed above in reference to FIG. 2C.

In some embodiments, the fiber matrix 140 may be formed byelectro-spinning or electrospraying a plurality of fibers onto an outersurface of a substrate, such as a core pin or an extrusion mandrel. Thecore pin or extrusion mandrel may be rotated while the fibers areelectro-spun onto the outer surface. In some embodiments, the fibermatrix 140 may be formed by a plurality of randomly aligned electro-spunor electrosprayed fibers. In some embodiments, fibers may have diametersin the range of about 0.1 micrometers to 2 micrometers, for example. Thefiber diameter size may be measured by taking the average size of thefibers. In some embodiments, a spacing between fibers of the fibermatrix 140 may create pores having an average pore diameter. In someembodiments, the fiber matrix 140 has an average pore diameter of atleast 0.1 micrometers.

In some embodiments, at least some of the plurality of fibers mayconsist of a single fiber extending a plurality of times between thefirst component 120 and the second component 122. Such a structure mayproduce loops of fibers in the fiber matrix 140 that may anchor thefirst portion 142 in the first component 120, possibly providing astronger joint structure.

In some embodiments, the fiber matrix 140 may form a cylinder coveringthe entirety of the first transition surface 130. In other embodiments,the fiber matrix 140 may cover only a portion of the first transitionsurface 130. In such embodiments, the fiber matrix 140 may be in theform of a series of rings, and/or a spiral extending much of the lengthof the lead body transition 124, and/or other forms.

According to some embodiments, interpenetration of the fiber matrix 140and the first material may be done while the first material is in aliquid state, for example, before it has solidified by cross-linking. Insome embodiments, the fibers forming the fiber matrix 140 may beelectro-spun directly into the first material. In other embodiments, thefiber matrix 140 may be formed on a core pin or mandrel as describedabove, and then the first material in a liquid state is molded orextruded over the fiber matrix 140. The first material may then besolidified to form the first component 120 with the first portion 142 ofthe fiber matrix 140 interpenetrated with the first material,mechanically fixing fiber matrix 140 within the first component 120.

In some embodiments, after the first material is solidified and thefirst component 120 is formed, the core pin or extrusion mandrel may beremoved. Removing the core pin or extrusion mandrel forms the firstlumen 128. The fiber matrix 140 can transfer with the first component120 because the fiber matrix 140 is interpenetrated with, andmechanically fixed to, first component 120. In other words, the fibermatrix 140 does not remain on the core pin or extrusion mandrel afterremoval of the core pin or extrusion mandrel.

FIG. 4 is a schematic cross-sectional view of an alternative embodimentof a joint structure connecting the first component 120 of the medicalelectrical lead 110, to the second component 122. FIG. 4 shows a portionof the joint structure including a fiber matrix 138 joining the firstcomponent 120 to the second component 122. The fiber matrix 138 isidentical to the fiber matrix 132 described above in reference to FIGS.3A-3C, except that it may be formed of a material that does not bondreadily to either the first material or the second material.

According to the embodiment shown in FIG. 4, the fiber matrix 148 mayinclude a first portion 148 and a second portion 150. The first portion148 may be connected to the first component 120, as with first portion140 described above in reference to FIGS. 3A-3C. Because the firstportion 148 of the fiber matrix 146 may be mechanically fixed to thefirst component 120, the fiber matrix 146 may be made of a material thatdoes not bond readily to the first material of the first component 120.In contrast to the embodiment described above in reference to FIGS.2A-2C, in the embodiment shown in FIG. 4, the second portion 150 may beinterpenetrated with the second material. In some embodiments a solution152 of the second material in a solvent may be interpenetrated with thesecond portion 150. In some embodiments, the solvent does not dissolveeither the first material of the first component 120 or the fiber matrix146. Once the solvent is evaporated, leaving behind the second material,the second portion 150 may be mechanically fixed to the second material.The second material of second component 122 may be easily bonded to theinterpenetrated second material from solution 152 by, for example, heatbonding, such that the interpenetrated second material becomes part ofthe second component 122. In some embodiments, once the interpenetratedsecond material from solution 152 becomes part of the second component122, the second portion 150 may directly contact the second component122, as there is no need for a third material between the second portion150 and the second component 122. Because the second portion 150 of thefiber matrix 146 may be mechanically fixed to the second component 122,the fiber matrix 146 may be made of a material that does not bondreadily to the second material.

In some embodiments as described above in reference to FIG. 4, the firstmaterial may be a silicone polymer, the second material may be apolyurethane polymer, and the fiber matrix 146 may be an aliphaticpolyamide polymer. The solvent may include tetrahydrofuran. In otherembodiments, the fiber matrix 146 may be a fluoropolymer, such aspoly(vinylidene fluoride-co-hexafluoropropene) (PVDF-HFP), orstyrene-isobutylene-styrene (SIBS).

Various modifications and additions can be made to the exemplaryembodiments discussed without departing from the scope of the presentinvention. For example, while the embodiments described above refer toparticular features, the scope of this invention also includesembodiments having different combinations of features and embodimentsthat do not include all of the described features. Accordingly, thescope of the present invention is intended to embrace all suchalternatives, modifications, and variations as fall within the scope ofthe claims, together with all equivalents thereof.

We claim:
 1. A joint structure between two components of an implantablemedical device, the joint structure comprising: a first component madeof a first material; a second component made of a second material; and afiber matrix including a plurality of fibers, the fiber matrix joiningthe first component to the second component, the fiber matrix including:a first portion of the fiber matrix connected to the first component,wherein the first portion of the fiber matrix is interpenetrated with,and mechanically fixed to, the first material; and a second portion ofthe fiber matrix connected to the second component; wherein the firstportion of the fiber matrix directly contacts the first material.
 2. Thejoint structure of claim 1, wherein the first material is a siliconepolymer, the second material is a polyurethane polymer, and the fibermatrix is a polyurethane polymer.
 3. The joint structure of claim 2,wherein at least some of the plurality of fibers in the second portionof the fiber matrix are distinctly identifiable within the secondcomponent.
 4. The joint structure of claim 3, wherein the second portionof the fiber matrix is connected to the second component by a heat bond.5. The joint structure of claim 1, wherein the second portion of thefiber matrix is interpenetrated with, and mechanically fixed to, thesecond material, and wherein the second portion of the fiber matrixdirectly contacts the second material.
 6. The joint structure of claim5, wherein the first material is a silicone polymer, the second materialis a polyurethane polymer, and the fiber matrix is an aliphaticpolyamide polymer.
 7. The joint structure of claim 1, wherein each fiberof the plurality of fibers has a diameter between 0.1 micrometers and 2micrometers.
 8. The joint structure of claim 1, wherein at least some ofthe plurality of fibers are randomly oriented.
 9. The joint structure ofclaim 1, wherein at least some of the plurality of fibers include asingle fiber extending a plurality of times between the first componentand the second component.
 10. A method for joining a first component anda second component of an implantable medical device, the methodcomprising: interpenetrating a first portion of a fiber matrix within afirst material, the first material being in a liquid state; forming thefirst component by solidifying the first material, wherein the firstportion of the fiber matrix is mechanically fixed within a portion ofthe first component and a second portion of the fiber matrix projectsfrom the first component; and connecting the second portion of the fibermatrix to the second component to join the first component to the secondcomponent.
 11. The method of claim 10, wherein interpenetrating thefirst portion of the fiber matrix within the first material includeselectro-spinning a fiber directly into the first material.
 12. Themethod of claim 10, wherein interpenetrating the first portion of thefiber matrix within the first material includes: electro-spinning atleast one fiber onto a substrate to form the fiber matrix; andovermolding the first material onto the fiber matrix on the substrate.13. The method of claim 10, wherein solidifying the first material is bycross-linking portions of the first material around portions of thefirst portion of the fiber matrix.
 14. The method of claim 10, whereinconnecting the second portion of the fiber matrix to the secondcomponent includes heat bonding the second portion of the fiber matrixto the second component.
 15. The method of claim 10, wherein connectingthe second portion of the fiber matrix to the second component includes:interpenetrating the second portion of the fiber matrix within a liquidsolution including a first portion of the second material; solidifyingthe first portion of the second material evaporating a solvent from theliquid solution such that the second portion of the fiber matrix ismechanically fixed within the first portion of the second component; andforming the second component by heat bonding a second portion of thesecond component to the first portion of the second component such thatat least a portion of the second portion of the fiber matrix isdistinctly identifiable within the second component.
 16. The method ofclaim 15, wherein the first material is a silicone polymer, the secondmaterial is a polyurethane polymer, and the fiber matrix is an aliphaticpolyamide polymer.
 17. An implantable medical device comprising: a firsttubular structure; a second tubular structure coaxial with the firsttubular structure; and a fiber matrix joining the first tubularstructure to the second tubular structure, the fiber matrix including: afirst portion of the fiber matrix interpenetrated within, andmechanically fixed to, the first tubular structure; and a second portionof the fiber matrix connected to the second tubular structure; whereinthe first portion of the fiber matrix directly contacts the firsttubular structure.
 18. The device of claim 17, wherein the secondtubular structure is at least partially within the first tubularstructure.
 19. The device of claim 17, wherein the first tubularstructure is made of a silicone polymer, the second tubular structure ismade of a polyurethane polymer, and the fiber matrix is made of apolyurethane polymer.
 20. The device of claim 17, wherein the firsttubular structure is a silicone polymer, the second tubular structure isa polyurethane polymer, and the fiber matrix is an aliphatic polyamidepolymer; and wherein the second portion of the fiber matrix isinterpenetrated with, and mechanically fixed to, the second tubularstructure, and wherein the second portion of the fiber matrix directlycontacts the second tubular structure.